Sheet metal punching apparatus



May 24, 1938; F. H. JOHNSON- SHEET METAL PUNCHING APPARATUS Filed April 50, 1937 2 Sheets-Sheet l Elma/whom awk/ ga/zmezz d Patented May 24, 1938 UNITED STATES PATENT OFFICE 2 Claims.

My invention relates to a hydraulic sheet metal punching apparatus for producing simultaneously, a large number of holes in sheet metal, such as 'rivet holes, or for punching out or punching up parts of sheet metal for any desired purpose.

The invention particularly provides a hydraulic stripper device carried by a hydraulically operated plunger and operative to withdraw the punch and the plunger from the work and means .for alternately connecting the hydraulic actuated parts with a source of supply of fluid under pressure. The invention eliminates the high resistant springs commonly used for withdrawing punches from the work and thus reduces the hydraulic pressure required to punch the work and at the same time, compress the springs.

The invention may be contained in structures of different forms and to illustrate a practical application of the invention, 1 have selected an apparatus containing the invention, as an example oi; the structures embodying the invention,

and shall describe the selected structure hereinafter.

The particular apparatus selected is shown in the accompanying drawings.

Fig. 1 illustrates a part of the apparatus where in a plurality of sheet metal punching devices are used for hydraulically forming a plurality of holes in sheet metal bent to a desired shape. Fig. 2 illustrates a view of a section of one of the devices shown in Fig. 1.

In the particular form of apparatus shown in the drawings, the punching devices are supported on a suitable bed or frame I and disposed at desired angles relative to each other according to the configuration of the sheet metal and the location of the points at which the holes are to be formed in the metal. The punching devices are individually supported on frames or brackets 2 that may be bolted to the bed or frame I. The frame I or brackets 2, or both, may be shaped into different forms according to the lines of holes to be formed and the angular relation of the parts in which the holes are to be formed by the different punches and enable the operation of the punches indirections at right angles to the surface of the metal. The sheet metal is located in position such that it may be pressed against a support or die or anvil during the punching operation. The support or frame or die is shaped to conform to the line along which the openings are to be formed in the sheet metal by the punches. In the form of construction shown, a plurality of anvils 4, in the form of ment of the punches. The anvils l are arranged in conformance to the line of holes to be formed in the sheet metal and in positions to support the metal while it is being punched. The anvils 4 are secured by bolts to the bed or frame I in opposing relation to the brackets 2 that support the punching devices.

The punching devices 5 are provided with cylinders I and pistons 8. The cylinders 'l are secured in the brackets 2. A plunger I0 is connected to each piston 8. The plunger l0 may be in the form of a crosshead connected to the outer end of the piston 8. Also, each punching device 5 is provided with a pair of cylinders l2 and pistons l4. Thecylinders l2 are secured to the ends of the plunger Ill and are carried with the plunger as it is reciprocated. The cylinders extend through the brackets 2 and are slidably supported therein and operate to guide the plunger as it is reciprocated. A pressure member [5 is connected to the pistons I4 and is moved against the work by the pistons 8 to engage and a hold the work during the punching operation. The pistons 8 and [4 are operated by fluid pressures in the cylinders l and I2. The flow of the fluid to the cylinder is controlled by a valve that may be operated by any suitable means for connecting the cylinders to a source of supply of fluid under pressure.

A valve I8 is suitably mounted with reference to the punching devices and is provided with a Any number of punches may be connected to each plunger. The punches extend into openings l9 formed in the pressure members IS. The work 25 is disposed intermediate the anvils l and the pressure members V I5. When the pistons 8 are operated they first move the pressure members l5 against the work to securely hold the work and then subsequently cause the punches to form openings in the work. The valve I8 is then operated to disconnect the cylinders I from the source and to connect the cylinders I2 with the source. The pistons l4 operate to press the pressure members IS with a greater pressure to draw the punches from the work and thereby strip the work from the punches. The pistons I move the plungers ill in a direction opposite to that in which they were moved by the operation of the pistons 8 until the punches have been pulled from the work, whereupon, the pressure members l5 and the plungers in are further moved from the work by the operation of suitable springs that engage the pistons l.

The pistons 8 have suitable heads 26 located in bushings 21 for guiding the outer ends oi the pistons and springs 28 are located intermediate the pistons 8 and the. inner ends of the bushings I 25. The springs 28 have merely a pressure sumcient to move the plungers l0, when the punches are released from the work, to remove the pressure members I5 away from the work and aflord sufllcient space between the pressure members and the anvils to place a succeeding piece or work in position to be punched by the succeeding simultaneous operation of the punching devices.

The cylinders I! are provided with the cylinder heads 29 and 30. The pistons I extend through the heads 29. The outer ends of the pistons it are threaded and are adiustably connected to the pressure members l5. They may be adjustably secured relative to the pressure members I! by the lock nuts 3|. The cylinders H are provided with springs 32- located intermediate the heads 30 and the pistons ll. If desired, the pistons ll may be provided with rods having heads TI that engage the pistons H. The springs 32 surround the rods 35 and operate to' maintain the pressure members ii at a limited distance from the plungers III and so as to locate the pressure members l5 against the work in advance of the engagement of the work ;by the punches. As the punches I 6 are further moved against and through the work, the springs 32, located in the cylinders l2, are compressed and press the pressure members l5 against the work.

I claim:

1. In a punching device, a punching cylinder, a punching piston located in the punching cylinder and having a piston rod extending through one end of the punching cylinder, a spring for spring pressing the punching piston towards the other end oi the punching cylinder, a member and a punch holder connected to the outer end oi. the piston rod, a pair of stripping cylinders carried on the member, stripping pistons located in the stripping cylinders, each of the stripping pistons having a piston rod extending through one end 0! its associated stripping cylinder, springs for spring pressing the stripping pistons toward the said ends of the stripping cylinders, a work engaging member connected to the ends of the piston rods of the stripping pistons, a punch connected to the punch holder, a die coacting with the punch to punch the work and means for directing fluid under pressure to the punching cylinder and the stripping cylinders to punch and strip the work from the punch.

2. In a punching apparatus, a plurality of punching devices each punching device comprising a punching cylinder, a punching piston located in the punching cylinder and having a piston rod extending through one end of the punching cylinder, a spring for spring-pressing the punching piston towards the other end of the punching cylinder, a member and a punch holder connected to the outer end of the piston rod, a pair 01 stripping cylinders carried on the member, stripping pistons located in the stripping cylinders, each of the stripping pistons having a piston rod extending through one end of the associated stripping cylinder, springs for spring pressing the stripping pistons toward the said ends of the stripping cylinders, a work engaging member connected to the ends of the piston rods of the stripping pistons, a punch connected to the punch holder, a die coacting with the punch to punch the work, a frame having parts for supporting the punching devices at desired angles relative to each other according to the contour and relative location of the portions of the work and means for directing fluid under pressure to each of the punching cylinders and to the stripping cylinders to punch and strip the work from the punches.

FREDERICK H. JOHNSON. 

